Andy Ruiz Jr caused one of the biggest upsets in heavyweight boxing history last nightHis opponent was Anthony Joshua, the IBF, WBO and WBA world champion, who was expected by many to steamroll the Mexican. Some bookmakers even had Joshua as a 1-25 favourite.However, despite a positive first few rounds from AJ, with the Brit even knocking his rival down in the third, Ruiz took control of the bout and floored Joshua no less than four times on his way to victory.By the time the seventh-round knockdown came, Ruiz had earned his triumph, and he will now go down in history for having caused a shock for the ages.Joshua, meanwhile, will have to lick his wounds and regroup after losing a fight that he fully expected to win.

He is by no means the first world champion to suffer such a setback, though. Mike Tyson and Lennox Lewis lost seemingly easy fights as the best in the business, against Buster Douglas and Hasim Rahman respectively.

And Joshua's compatriot Lewis has sent a message of support to Joshua, whilst also praising Ruiz at the same time.

Via Twitter, he said: “I do want to say congrats to Andy Ruiz for becoming the first EVER Mexican Heavyweight champ! #Respect To AJ... Pick urself up and learn from this. Don’t worry, you will bounce back! #JoshuaRuiz”

What makes this result even more surprising is the fact that Ruiz shouldn't have even been there in the first place.

Originally, Joshua was meant to face Jarrell Miller for his maiden US fight, but the American failed three drug tests and was therefore unable to make the bout. Ruiz was brought in as a last minute replacement to keep the date alive.

It already promised to be a compelling year for the boxing heavyweight division, and now, it is even more so. It will be interesting to see how it develops over the coming months, with Joshua, Deontay Wilder, Tyson Fury and now Ruiz all in the mix at the top.